If David Stern had his way, LeBron James wouldn't play in the National Basketball Association next season.

The commissioner wants a minimum age of 20 for NBA employment. The idea isn't getting much traction, but it comes from the same Mr. Stern who negotiated a labor deal that gives talented young players all the incentive in the world to turn pro.

Mr. James, an 18-year-old hyped as the best ever to come out of high school, was the top pick in Thursday's NBA draft, going to the Cleveland Cavaliers.

Mr. James wouldn't be the only young player shut out under the proposed minimum age. Eight of Thursday's 29 first-rounders were teenagers.

The second pick, going to the Detroit Pistons, was Darko Milicic, an 18-year-old center from Serbia. Carmelo Anthony, a 19-year old who led Syracuse to the national title as a freshman, went third to the Denver Nuggets.

The debate over young players often centers on what they'll miss in skipping college and whether they're ready for the NBA's glamour and grind. When it comes to pure dollars and sense – that is, maximizing lifetime earnings – there can be little doubt about what's smart:

Get to the NBA as fast as you can.

Top young players' earnings are restricted by a wage scale in their first four years. They've got to serve that time before they can cash in on the sweet spot of an NBA career, where earnings ceilings jump for second and third contracts.

Agent Arn Tellem says today's 18-year-old phenom can get his first big deal at age 22. The next might come at age 28 or 29, still during his prime.

"If he were to attend four years of college, he would enter the NBA at 22 and not be eligible for free agency until 26," he said. "At the end of that first major deal, he would be 33 – far less likely to command another major one."

It's all spelled out in the labor deal Mr. Stern negotiated in 1998. First-round picks sign contracts guaranteed for three seasons, with a team option for a fourth. Minimum and maximum pay are stipulated for each spot in the draft's pecking order.

If he signs for the maximum, Mr. James will get $4 million as a rookie and $18.8 million in his first four years. The best Mr. Milicic can do is $16.8 million. For Mr. Anthony, it's $15.1 million.

Could be bigger

Those are big numbers, but they're well below what first rounders could command if they were free to negotiate their pay, said Dan Rosenbaum, an economist at the University of North Carolina in Greensboro.

Assuming this year's rookies are star material, Mr. Rosenbaum figured that their lifetime NBA earnings would have been greatly diminished if they had waited to go professional.

Mr. James would have lost $73 million, or about 30 percent of lifetime earnings, if he had played four years of college. The loss would have been $35 million if he had played in college until age 20.

Mr. Milicic would have lost only slightly less.

And Mr. Anthony, a year older, would have lost $54 million if he had played at Syracuse for four years and $16 million if he had played there until he was 20.

Easy to figure

It's not hard to figure out how the NBA ended up with a pay structure skewed against young stars. The union represents the interests of established players, not future rookies. Fed up with huge contracts to untested rookies, the older players went along with Mr. Stern on the wage scale.

Money shifted from younger players to older ones, Mr. Rosenbaum said. Players picked in last year's first round will earn $189 million in their first four years, or less than first rounders before the wage scale went into place in 1994. Veterans with five or more years in the league, meanwhile, saw pay jump 185 percent.

During the NBA playoffs, Mr. Stern said his proposal for a minimum age wasn't getting much support. Don't count it out, though, because future rookies won't be at the bargaining table when the NBA renews its labor deal after next season.